Outcomes for Patients Undergoing Transcatheter Edge-to-Edge Repair for Functional Mitral Regurgitation
By Michael H. Crawford, MD, Editor
SYNOPSIS: Researchers analyzed transcutaneous mitral valve repair in patients with moderate-to-severe or worse mitral valve regurgitation caused by cardiomyopathy and heart failure despite maximally tolerated guideline-directed medical therapy. Compared to medical therapy alone, undergoing repair resulted in fewer heart failure and other cardiovascular disease hospitalizations and significantly more time free of hospitalization and death.
SOURCE: Giustino G, Camaj A, Kapadia SR, et al. Hospitalizations and mortality in patients with secondary mitral regurgitation and heart failure: The COAPT trial. J Am Coll Cardiol 2022;80:1857-1868.
The Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation (COAPT) trial was an international, open-label, multicenter, randomized study of the effects of transcatheter edge-to-edge repair (TEER) of the mitral valve with the MitraClip. The results indicated a lower rate of heart failure hospitalizations (HFH) and higher survival rates compared to guideline-directed medical therapy (GDMT) alone in selected patients with HF and severe mitral regurgitation (MR).
In this COAPT substudy, Giustino et al sought to further characterize the effects of TEER on cause-specific hospitalizations in COAPT and to evaluate whether the reduction in MR severity with TEER modulates the effect of subsequent hospitalizations on mortality.
The 614 patients enrolled in COAPT had been diagnosed with ischemic or non-ischemic cardiomyopathy (ejection fraction 20% to 50%), moderate-to-severe or worse MR, or New York Heart Association (NYHA) functional class II-IV HF despite maximally tolerated GDMT. Patients with left ventricular end-diastolic dimensions (LVEDD) greater than 7 cm, severe pulmonary hypertension, severe tricuspid regurgitation (TR), or moderate-to-severe right ventricular (RV) dysfunction were excluded. At the time of this analysis, all patients had completed two years of the planned five-year follow-up, and 71% had experienced one or more hospitalizations.
TEER-treated patients compared to patients treated with GDMT alone resulted in fewer HFH (35% vs. 56%; HR, 0.51; 95% CI, 0.39-0.66) and fatal HFH (6.5% vs. 12.6%; HR, 0.47; 95% CI, 0.26-0.85). Also, TEER-treated patients spent an average of two more months alive and out of the hospital (581 days vs. 519 days; P = 0.002). All cardiovascular hospitalizations were consistently and independently associated with higher two-year mortality rates in both groups.
In addition, patients who experienced any hospitalization recorded higher rates of comorbidities, such as chronic kidney disease and atrial fibrillation. They scored higher on the Society of Thoracic Surgeons scale and logged higher baseline brain natriuretic peptide values. They recorded lower Kansas City Cardiomyopathy Questionnaire (KCCQ) scores and shorter six-minute walk distances. Finally, they experienced more severe MR and logged higher RV systolic pressures.
The authors concluded selected patients with HF and moderate-to-severe functional MR who underwent TEER recorded lower rates of HFH and spent significantly more time alive and out of the hospital than GDMT patients in the COAPT trial. Also, HFH was strongly associated with mortality, regardless of the treatment group.
As COAPT showed, functional MR caused by cardiomyopathy carries a poor prognosis, even with GDMT. The rate of hospitalizations for HF or other cardiovascular issues was high during the two years of follow-up in COAPT. Importantly, this was a predictor of mortality, even if the patient survived the hospitalization.
Hospitalizations for non-cardiovascular issues did not predict mortality. TEER, which only addresses MR and not the cardiomyopathy per se, remarkably reduced hospitalization rates, mainly driven by decreases in HFH compared to GDMT alone. Accordingly, the TEER group logged more days free of hospitalization or mortality than the GDMT group. Also, they scored lower on NYHA and KCCQ assessments and recorded longer six-minute walk distances. Considering GDMT was at the same intensity in both groups, one might conclude alleviating the amount of MR favorably affects LV function. Although the authors did not present data to support a change in LV function in this report, it is interesting that three variables were worse in those hospitalized over the two years compared to those not: the severity of MR, TR, and RV systolic pressure — but not LV ejection fraction (EF). Perhaps the main benefit of TEER in functional MR is lowering back pressure on the RV.
There were limitations to the COAPT trial. The patient population was relatively small and the follow-up period short. The patients entered in the study were highly selected. Of note, those with LVEF < 20% or LVEDD > 7 cm were excluded. Also, GDMT is a moving target. There were few patients in COAPT on neprilysin inhibitors and none on sodium-glucose cotransporter 2 inhibitors. In addition, two-thirds or more of both groups had some device implanted, but it was not specified whether these were implantable defibrillators or cardiac resynchronization devices. Either could have affected the study endpoints. Finally, most patients experienced an ischemic cardiomyopathy, but no details were provided about whether any showed evidence of ongoing ischemia and would be candidates for revascularization.
At this point, carefully selected patients with moderate-to-severe or worse MR secondary to an LV cardiomyopathy who are inadequately responsive to maximally tolerated GDMT, including revascularization and CRT, and are not living with an end-stage LV (EF less than 20% or LVEDD greater than 7 cm) should be considered for the MV TEER procedure.
Researchers analyzed transcutaneous mitral valve repair in patients with moderate-to-severe or worse mitral valve regurgitation caused by cardiomyopathy and heart failure despite maximally tolerated guideline-directed medical therapy. Compared to medical therapy alone, undergoing repair resulted in fewer heart failure and other cardiovascular disease hospitalizations and significantly more time free of hospitalization and death.
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